Digitizer with high accuracy of identifying position

Abstract

Provided is a digitizer with high accuracy of identifying a position, and more particularly, to a digitizer with high accuracy of identifying a position, in which a plurality of magnetic force sensors are installed to collect a plurality of pieces of position information regarding a magnetic force pen and a position of the magnetic force pen is determined by using only position information selected according to a specific reference. Since only information with high reliability, among pieces of position information of the magnetic force pen measured by the plurality of magnetic force sensors, is used, accuracy of identifying a position of the magnetic force pen may be increased.

1 . A digitizer with high accuracy of identifying a position, in which a plurality of magnetic force sensors are installed to collect a plurality of pieces of position information regarding a magnetic force pen, and a position of the magnetic force pen is determined by using only position information selected according to predetermined selection reference among the plurality of pieces of collected position information, the digitizer comprising:
 a touchscreen configured to display an image;   a magnetic force pen configured to move at an upper side of a front surface of the touchscreen, while a magnetic material generates a three-dimensional (3D) magnetic field distribution;   a plurality of magnetic force sensors installed inside a case and configured to measure a direction and a magnitude of a 3D magnetic field generated by the magnetic force pen; and   a control unit configured to select a portion of the plurality of pieces of position information collected by the plurality of magnetic force sensors to determine a position of the magnetic force pen,   wherein the selection reference for the control unit to select the position information is a magnitude value of a magnetic field vector, and the control unit calculates a position of the magnetic force pen by selecting one or two pieces of position information having the largest magnitude value of the magnetic field vector among the pieces of position information input from the plurality of magnetic force sensors.   
     
     
         2 . The digitizer of  claim 1 , wherein when the two pieces of position information having the largest magnitude value of the magnetic field vector are selectively calculated, the control unit calculates a position of the magnetic force pen by calculating a function of X, Y, and Z-axis directional components and a tilt from magnetic field vectors obtained from the two pieces of selected position information. 
     
     
         3 . The digitizer of  claim 1 , wherein when the magnetic force sensor for collecting the position information is changed as the magnetic force pen moves, the control unit corrects a position of the magnetic force pen through a position correction algorithm of adding a value measured by the magnetic force sensor and a value estimated on the basis of past information of the magnetic force pen by applying different weight values thereto. 
     
     
         4 . The digitizer of  claim 3 , wherein the position correction algorithm is any one of the Kalman filter and the Particle filter.